An optical waveguide circuit device having a waveguide formed from a core such as shown in FIG. 4 is used in various uses in an optical communication field. This waveguide is generally formed from a silica-based glass on the substrate. In the optical waveguide circuit device of this kind, various functions can be fulfilled by a difference in the waveguide. The substrate of a single crystal such as a silicon substrate, etc. is generally used as the above substrate.
The present invention provides a novel optical waveguide circuit device. The optical waveguide circuit device of the invention comprises:
a substrate having a cleavage plane;
a waveguide formed from a core on said substrate; and
an incision line constructed by a groove or (and) a separating slit formed by crossing at least one portion of the core of said waveguide;
wherein a face of said incision line is set to a face different from the cleavage plane of said substrate.